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Merged
merged 3 commits into from
Jan 7, 2020
Merged

Fix "did you mean" hinting #7895

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1752609
Refactor "did you mean" hinting
odersky Jan 5, 2020
2c97437
Fix Levenshtein distance calculation
odersky Jan 5, 2020
63f87ee
Fix typo
odersky Jan 6, 2020
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78 changes: 34 additions & 44 deletions compiler/src/dotty/tools/dotc/reporting/diagnostic/messages.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -314,56 +314,46 @@ object messages {

val msg: String = {
import core.Flags._
val maxDist = 3
val decls = site.decls.toList
.filter(_.isType == name.isTypeName)
.flatMap { sym =>
if (sym.flagsUNSAFE.isOneOf(Synthetic | PrivateLocal) || sym.isConstructor) Nil
else List((sym.name.show, sym))
}
val maxDist = 3 // maximal number of differences to be considered for a hint
val missing = name.show

// The names of all non-synthetic, non-private members of `site`
// that are of the same type/term kind as the missing member.
def candidates: Set[String] =
for
bc <- site.widen.baseClasses.toSet
sym <- bc.info.decls.filter(sym =>
sym.isType == name.isTypeName
&& !sym.isConstructor
&& !sym.flagsUNSAFE.isOneOf(Synthetic | Private))
yield sym.name.show

// Calculate Levenshtein distance
def distance(n1: Iterable[?], n2: Iterable[?]) =
n1.foldLeft(List.range(0, n2.size)) { (prev, x) =>
(prev zip prev.tail zip n2).scanLeft(prev.head + 1) {
case (h, ((d, v), y)) => math.min(
math.min(h + 1, v + 1),
if (x == y) d else d + 1
)
}
}.last

// Count number of wrong characters
def incorrectChars(x: (String, Int, Symbol)): (String, Symbol, Int) = {
val (currName, _, sym) = x
val matching = name.show.zip(currName).foldLeft(0) {
case (acc, (x,y)) => if (x != y) acc + 1 else acc
}
(currName, sym, matching)
}

// Get closest match in `site`
def closest: List[String] =
decls
.map { (n, sym) => (n, distance(n, name.show), sym) }
.collect {
case (n, dist, sym)
if dist <= maxDist && dist < (name.toString.length min n.length) =>
(n, dist, sym)
}
.groupBy(_._2).toList
.sortBy(_._1)
.headOption.map(_._2).getOrElse(Nil)
.map(incorrectChars).toList
.sortBy(_._3)
.map(_._1)
// [Martin] Note: I have no idea what this does. This shows the
// pitfalls of not naming things, functional or not.
def distance(s1: String, s2: String): Int =
val dist = Array.ofDim[Int](s2.length + 1, s1.length + 1)
for
j <- 0 to s2.length
i <- 0 to s1.length
do
dist(j)(i) =
if j == 0 then i
else if i == 0 then j
else if s2(j - 1) == s1(i - 1) then dist(j - 1)(i - 1)
else (dist(j - 1)(i) min dist(j)(i - 1) min dist(j - 1)(i - 1)) + 1
dist(s2.length)(s1.length)

// A list of possible candidate strings with their Levenstein distances
// to the name of the missing member
def closest: List[(Int, String)] = candidates
.toList
.map(n => (distance(n.show, missing), n))
.filter((d, n) => d <= maxDist && d < missing.length && d < n.length)
.sorted // sort by distance first, alphabetically second

val finalAddendum =
if addendum.nonEmpty then addendum
else closest match {
case n :: _ =>
case (d, n) :: _ =>
val siteName = site match
case site: NamedType => site.name.show
case site => i"$site"
Expand Down
72 changes: 72 additions & 0 deletions tests/neg/name-hints.check
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Original file line number Diff line number Diff line change
@@ -0,0 +1,72 @@
-- [E008] Member Not Found Error: tests/neg/name-hints.scala:6:15 ------------------------------------------------------
6 | val x1 = Int.maxvalue // error
| ^^^^^^^^^^^^
| value maxvalue is not a member of object Int - did you mean Int.MaxValue?
-- [E008] Member Not Found Error: tests/neg/name-hints.scala:7:15 ------------------------------------------------------
7 | val x2 = Int.MxValue // error
| ^^^^^^^^^^^
| value MxValue is not a member of object Int - did you mean Int.MaxValue?
-- [E008] Member Not Found Error: tests/neg/name-hints.scala:8:15 ------------------------------------------------------
8 | val x3 = Int.MaxxValue // error
| ^^^^^^^^^^^^^
| value MaxxValue is not a member of object Int - did you mean Int.MaxValue?
-- [E008] Member Not Found Error: tests/neg/name-hints.scala:10:13 -----------------------------------------------------
10 | val d1 = O.abcd // error
| ^^^^^^
| value abcd is not a member of object O - did you mean O.abcde?
-- [E008] Member Not Found Error: tests/neg/name-hints.scala:11:13 -----------------------------------------------------
11 | val d2 = O.abc // error
| ^^^^^
| value abc is not a member of object O - did you mean O.abcde?
-- [E008] Member Not Found Error: tests/neg/name-hints.scala:12:13 -----------------------------------------------------
12 | val d3 = O.ab // error, no hint since distance = 3 > 2 = length
| ^^^^
| value ab is not a member of object O
-- [E008] Member Not Found Error: tests/neg/name-hints.scala:13:13 -----------------------------------------------------
13 | val s1 = O.Abcde // error
| ^^^^^^^
| value Abcde is not a member of object O - did you mean O.abcde?
-- [E008] Member Not Found Error: tests/neg/name-hints.scala:14:13 -----------------------------------------------------
14 | val s3 = O.AbCde // error
| ^^^^^^^
| value AbCde is not a member of object O - did you mean O.abcde?
-- [E008] Member Not Found Error: tests/neg/name-hints.scala:15:13 -----------------------------------------------------
15 | val s3 = O.AbCdE // error
| ^^^^^^^
| value AbCdE is not a member of object O - did you mean O.abcde?
-- [E008] Member Not Found Error: tests/neg/name-hints.scala:16:13 -----------------------------------------------------
16 | val s3 = O.AbCDE // error, no hint
| ^^^^^^^
| value AbCDE is not a member of object O
-- [E008] Member Not Found Error: tests/neg/name-hints.scala:17:13 -----------------------------------------------------
17 | val a1 = O.abcde0 // error
| ^^^^^^^^
| value abcde0 is not a member of object O - did you mean O.abcde?
-- [E008] Member Not Found Error: tests/neg/name-hints.scala:18:13 -----------------------------------------------------
18 | val a2 = O.abcde00 // error
| ^^^^^^^^^
| value abcde00 is not a member of object O - did you mean O.abcde?
-- [E008] Member Not Found Error: tests/neg/name-hints.scala:19:13 -----------------------------------------------------
19 | val a3 = O.abcde000 // error
| ^^^^^^^^^^
| value abcde000 is not a member of object O - did you mean O.abcde?
-- [E008] Member Not Found Error: tests/neg/name-hints.scala:20:13 -----------------------------------------------------
20 | val a4 = O.abcde0000 // error, no hint
| ^^^^^^^^^^^
| value abcde0000 is not a member of object O
-- [E008] Member Not Found Error: tests/neg/name-hints.scala:22:13 -----------------------------------------------------
22 | val y1 = O.x // error, no hint
| ^^^
| value x is not a member of object O
-- [E008] Member Not Found Error: tests/neg/name-hints.scala:23:13 -----------------------------------------------------
23 | val y2 = O.xY // error
| ^^^^
| value xY is not a member of object O - did you mean O.xy?
-- [E008] Member Not Found Error: tests/neg/name-hints.scala:24:13 -----------------------------------------------------
24 | val y3 = O.xyz // error
| ^^^^^
| value xyz is not a member of object O - did you mean O.xy?
-- [E008] Member Not Found Error: tests/neg/name-hints.scala:25:13 -----------------------------------------------------
25 | val y2 = O.XY // error, no hint
| ^^^^
| value XY is not a member of object O
26 changes: 26 additions & 0 deletions tests/neg/name-hints.scala
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Original file line number Diff line number Diff line change
@@ -0,0 +1,26 @@
object O with
val abcde: Int = 0
val xy: Int = 1

object Test with
val x1 = Int.maxvalue // error
val x2 = Int.MxValue // error
val x3 = Int.MaxxValue // error

val d1 = O.abcd // error
val d2 = O.abc // error
val d3 = O.ab // error, no hint since distance = 3 > 2 = length
val s1 = O.Abcde // error
val s3 = O.AbCde // error
val s3 = O.AbCdE // error
val s3 = O.AbCDE // error, no hint
val a1 = O.abcde0 // error
val a2 = O.abcde00 // error
val a3 = O.abcde000 // error
val a4 = O.abcde0000 // error, no hint

val y1 = O.x // error, no hint
val y2 = O.xY // error
val y3 = O.xyz // error
val y2 = O.XY // error, no hint